CVE-2016-10832 in cPanel
Summary
by MITRE
cPanel before 55.9999.141 allows FTP cPHulk bypass via account name munging (SEC-102).
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Analysis
by VulDB Data Team • 11/20/2023
The vulnerability identified as CVE-2016-10832 affects cPanel versions prior to 55.9999.141 and represents a significant security flaw in the cPHulk brute force protection system. This issue enables attackers to bypass FTP account protection mechanisms through a technique known as account name munging, which exploits weaknesses in how the system validates and processes user credentials. The vulnerability specifically targets the cPHulk brute force protection system that is designed to prevent unauthorized access attempts by monitoring and blocking repeated login failures. The security advisory SEC-102 highlights that this bypass mechanism allows malicious actors to circumvent the intended protection measures that should have been in place to prevent credential stuffing and brute force attacks against FTP accounts.
The technical flaw stems from improper input validation and sanitization within the cPHulk system's account name handling logic. When users attempt to log in to FTP accounts, the system performs checks to prevent excessive login attempts that could indicate a brute force attack. However, the vulnerability allows attackers to manipulate account names in such a way that the system fails to properly recognize or block these malicious attempts. Through account name munging techniques, attackers can alter the format or encoding of account names in ways that bypass the validation mechanisms. This manipulation can involve encoding characters, using special sequences, or altering the presentation format of account names to evade detection by the brute force protection system. The flaw essentially allows attackers to perform unlimited login attempts against FTP accounts without triggering the expected security protections that should have been activated.
The operational impact of this vulnerability is substantial for organizations using cPanel systems, as it fundamentally undermines the security controls designed to protect against automated attack vectors. Organizations relying on cPanel for hosting services face increased risk of unauthorized FTP account access, which can lead to complete compromise of web hosting environments. The bypass capability means that attackers can systematically attempt to guess FTP credentials without the system's built-in protections functioning correctly. This creates opportunities for data theft, website defacement, server compromise, and potential lateral movement within compromised hosting environments. The vulnerability is particularly dangerous because it affects the core authentication protection mechanisms that are supposed to be the first line of defense against automated attack attempts. Security operations teams may not be aware that brute force attacks are succeeding because the system fails to detect or block the malicious activity, leading to false security confidence and delayed incident response.
Organizations should immediately upgrade to cPanel version 55.9999.141 or later to remediate this vulnerability, as no effective workarounds exist for the underlying issue. The mitigation strategy involves comprehensive system updates and verification of the updated configuration to ensure that cPHulk protection is functioning correctly. Security teams should conduct immediate audits of their FTP access logs to identify any suspicious activity that may have occurred during the vulnerability window, particularly looking for patterns of repeated login attempts against multiple accounts. Network security measures such as firewall rules and intrusion detection systems should be reviewed to ensure that additional protections are in place to detect and block brute force attempts. The vulnerability aligns with CWE-284 Access Control Issues and represents a failure in proper authentication control enforcement, while also mapping to ATT&CK technique T1110 Brute Force which covers credential brute force attacks. Organizations should also consider implementing additional authentication layers such as multi-factor authentication for FTP access, IP address restrictions, and regular security monitoring to prevent exploitation of similar vulnerabilities in other systems.